2015/10/16 [例1]单摆 Length Mass m ml+mgsin=0 平衡位置(Equilibrium position)O=0 sin0≈0 很小摆动(Nee swing) mle+mg=0 School of Mechanical Engineering ME369-lecture 5.3 Shanghai Jiao Tong University Fal12015 [例2-1]液位系统 dh o-0 A (横载面积) g.=a√h 取消中间变量Q。 += dt A A School of Mechanical Engineering ME369-lecture 5.3 Shanghai Jiao Tong University Fall 2015 22015/10/16 2 ME369-lecture 5.3 Fall 2015 School of Mechanical Engineering Shanghai Jiao Tong University [例1]单摆 ml mg     sin 0   0 很小摆动（Wee swing） sin   ml mg     0 平衡位置（Equilibrium position） ME369-lecture 5.3 Fall 2015 School of Mechanical Engineering Shanghai Jiao Tong University d 1 d r h a h Q t A A   取消中间变量Qc （横载面积） d d Qr c A h Q t   Q h c  a [例2-1]液位系统